1. Field of the Invention
The present invention relates to vehicle positioning and particularly, but not exclusively, to a method of determining the position of a part of a vehicle.
2. Description of the Prior Art
It is important that certain parts of a vehicle, for example drive components such as axles, drive shafts and engine cross members on which the engine may be mounted, are correctly positioned with respect to one another and are correctly aligned. Failure to ensure this can result in abnormal driving characteristics for the vehicle and/or excessive wear on the drive parts.
When a vehicle is initially assembled, the various parts are positioned and aligned by means of a jig assembly in a manner which is well known in the art. During the vehicle""s useful lifetime, however, it may be necessary for some of its parts to be removed, adjusted or replaced. It is essential that when the parts are refitted, they are correctly positioned and aligned with respect to one another.
Heretofore, it has been necessary to position and align replaced parts by means of a jig assembly, which is both expensive and time consuming. The present invention seeks to provide an improved method and apparatus for determining the position of a part of a vehicle.
According to one aspect of the present invention there is provided a method of determining the position of a part of a vehicle, the method comprising:
measuring the distance from a first measuring location to each of a plurality of measuring points associated with said part;
measuring the distance from a second measuring location to each of said measuring points;
calculating the position of each of said measuring points relative to a fixed location; and
comparing the position of each of said measuring points relative to said fixed location so as to determine the position of said part in said vehicle.
Preferably, the step of calculating includes calculating the position of a datum line relative to which the position of the part is to be determined.
The step of calculating may further include calculating the position of the intersection between the datum line and a line joining a respective measuring point and the datum line and which is perpendicular thereto.
The step of comparing may include comparing the positional distance along the datum line of the intersections with the datum line of two or more lines extending between the datum line and measuring points associated with a common part.
Conveniently, if the positional distances are the same, the part is deemed to be perpendicular to the datum line.
According to another aspect of the present invention there is provided measuring apparatus for locating a position on a vehicle, the apparatus comprising:
a main body having attachment means at one end thereof for attaching said body to said vehicle;
an elongate member extending substantially from said main body and universally pivotably mounted to pivot relative to the main body about a pivot point at a central point of the attachment means;
fixing means for releasably fixing the position of the elongate member relative to the main body; and
a measuring position located at a predetermined position along the elongate member;
wherein the apparatus is arranged such that, in use, the measuring position lies vertically below said central point.
Preferably, the elongate member is pivotably mounted by means of a wire attached at one end to the member and at the other end to said central point.
The measuring position may comprise a groove or other means in said elongate member for engagement with a part of an associated measuring unit.
The apparatus may further comprise checking means mounted on said elongate member for checking the verticality thereof.
The checking means may comprise a spherical spirit level, or an electronic levelling device, preferably mounted for axial rotation about said elongate member.